Pulse Width Modulation – Circuit Skills

PWM Controller: Control Devices Via a Digital Signal

By Collin Cunningham

Pulse Width Modulation (PWM) is a very clever way to use electricity to control analog devices via a digital signal. It's a very simple method and is very efficient in driving motors, lamps, LEDs and more!

A perfect example of using PWM is if you've ever faded an LED with an Arduino:

Fading – Demonstrates the use of the analogWrite() function in fading an LED off and on. AnalogWrite uses pulse width modulation (PWM), turning a digital pin on and off very quickly, to create a fading effect.

However, you don't need a microcontroller to generate a PWM signal. The 555 timer chip can be configured to modulate its output duty cycle in response to a potentiometer – with the help of some simple circuitry.

For a more robust solution, you may want to consider the DC to Pulse Width Modulator kit suitable for sending up to 6.5A of current and built around the Motorola SG3525 – a chip dedicated to the art of PWM.

Of course, Collin would be denying his own nature if he didn't mention at least one audio-related application. PWM comes in handy for generating simple sounds and melodies from a microcontroller.